What is the meaning of Bittern?

Several bird species in the Botaurinae subfamily of the heron family Ardeidae.

The liquor remaining after halite (common salt) has been harvested from saline water (brine).

The saline substance added to soy milk to coagulate it as a primary step in the production of tofu.

A very bitter compound of quassia, cocculus indicus, etc., used by fraudulent brewers in adulterating beer.

Source: wiktionary.org